1. Field of the Invention
The invention relates to a method for instant recognition of traffic lights countdown image that can quickly scan and confirm the circular feature of a traffic light, and retrieve the countdown image thereof by calculating the displacement ratio from the circular feature, then process the countdown image to display a feature image thereof and bring out the recognition result.
2. Description of the Related Art
Traffic lights have red, yellow, and green lights, among which the red and green lights may have countdown function to remind the drivers when the lights are about to change, so as to eliminate safety concerns during the driving.
Nevertheless, the drivers may lose attention to the countdown of traffic lights due to poor sight or distraction when driving, and thus cause irreparable loss. Also, optical illusion may happen owning to long time driving or exhaustion; but the optical illusion can be remedied by machine vision to recognize the status of the countdown.
However, there are still some defects for machine vision to recognize the countdown image of traffic lights because of unexpected situations caused by traffic and environment variation. Firstly, the countdown has different image of numbers with the passing of time; consequently, the machine vision has to process different contours of the numbers individually. When the machine vision cannot proceed with the image of numbers in time, it cannot further proceed with the recognition, therefore decreasing its reliability. Secondly, when the ambient light is weak, the retrieved image may have diffraction areas and result in difficulty in retrieving the exact image and conversing the image to binary mode in accordance with its features. Such problem cannot be solved even if the image is enhanced. Besides, the countdown image is conversed from RGB image to greyscale image, but the LED light source emitting the countdown numbers would cause detailed and undetectable changes of the greyscale image. Hence, the countdown image can be difficult to recognize due to the effects from the ambient lights, and the contours of the figures are different, making the recognizing process even more complicated and the entire process is therefore slower.